SDAM select should return copies of server descriptions
Refactor of cluster select and preselect
New networking functions
Cleaning up TODOS in client code
Support for SDAM/SS-related methods in collection
Stray TODOs in read prefs
Misc glue and documentation
Expose server descriptions by id to client classes
More stray TODOs glued up
fixed up scanner and async interface
with in_progress guard
Glue up tests
working
working
oh god... in pieces